单项选择题

Fly ash can partly take the place of （）.

A．paving material
B．cement
C．concrete
D．the coal by-product

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热门试题

单项选择题

Which of the following statements can best be inferred from the passage（）

A．Fishes only "speak" to communicate with each other.
B．Researches are now being made to study the significance of fish sounds.
C．Sea animals have a sharper hearing ability than men.
D．Sounds made by fish cannot be transmitted through the air.

单项选择题

What was Helen Keller like when Miss Sullivan met her（）

A．She was quiet and shy.
B．She was bright and friendly.
C．She was weak from illness.
D．She was uncontrollabl